This year's overall winner was Martin Pugh of Australia, for his capture of the M51 whirlpool galaxy (third photo above). The observatory's public astronomer Marek Kukula toasted the photo:

“The photographer has made the most of exceptionally good atmospheric conditions to capture an astonishing range of detail in his image of this iconic galaxy; the beautiful spiral structure, dark lanes of dust, and the way the pink clouds of hydrogen really stand out – it’s a remarkable achievement by an amateur astronomer; one of the best images of M51 that I’ve seen.”

The best images, including the six winners shown above, will be on show at the observatory until 5 February 2013. Entrance is free.